1. Field of the Invention
This invention relates to direct-current amplifiers and more particularly, to improvements in direct-current amplifiers to compensate for zero offsets due to generation of pyroelectric voltages.
2. Description of the Prior Art
The pyroelectric effect experienced with certain crystalline solids is a temperature dependent function of the polarization of such solids. When the temperature of the solid changes, a voltage is developed across it. It is recognized that the zero offset associated with high gain or low level direct-current amplifiers is principally a result of variations within the amplifiers themselves; however, when high gain, high input impedance amplifiers are used in conjunction with capacitors at the input circuitry, the pyroelectric effect becomes important. A zero offset may occur in such instances due to the generation of pyroelectric voltages. The dielectric materials in such capacitors exhibit spontaneous electric polarization. The internal dipole moment changes with temperature and produces a temperature dependent charge distribution. This in turn manifests itself as an offset voltage.